FIG. 1 (Prior Art) is a diagram of an interactive television system involving several different types of receiver units 100-104 that display information resources and television video. Receiver unit 100 is a personal computer that includes a specialized tuner and decoder expansion card. An example of one such expansion card is available from DirecTV, Inc, a unit of Hughes Electronics Corporation. Television video 105 is broadcast from a broadcaster""s transmitting antenna 106 to a receiving antenna 107 of a satellite uplink station 108. The satellite uplink station 108 receives the television video on receiving antenna 107 and transmits the television video 105 to a satellite 109 via a transmitting dish 110. Satellite 109 in turn relays the television video 105 to a small satellite dish 111 of receiver unit 100. A viewer is able to view the television video 105 using the screen of the personal computer of receiver unit 100 as a display device. Rather than viewing the television video, the viewer can choose to view Internet content. Receiver unit 100 sends a request for the desired Internet content via an Internet connection 112, the Internet 113, and an Internet connection 114, to uplink station 108. Uplink station 108 receives the request, retrieves the requested Internet content from the Internet 113 via Internet connection 114, and sends the requested Internet content to receiver unit 100 via satellite 109.
Receiver unit 101 is another example of a DirecTV(copyright) receiver unit having a special tuner and decoder expansion card and small satellite dish. Although receiver unit 101 is not connected to the Internet, receiver unit 101 can nevertheless display certain information resources and/or Internet content that is provided by the uplink station 108. An electronic newspaper is an example of such an information resource. Uplink station 108 retrieves the information resource (the electronic newspaper) from the Internet via its Internet connection 114, and then transmits that information resource to receiver unit 101 by encoding the information resource into broadcast television video signal 105. Receiver unit 101 receives the broadcast television video signal 105, decodes it to recover the information resource, and displays the information resource for viewing. A viewer is therefore able to switch from watching television to browsing through the various pages of the electronic newspaper even though receiver unit 101 has no connection to the Internet.
In contrast to DirecTV(copyright) receiver units 100 and 101 which principally display either television content or an information resource, receiver units 102-104 are considered interactive television receiver units. In interactive television, information from an information resource may be displayed along with television video in a synchronized fashion. When information is to be displayed at a point in the television video, a communication called a xe2x80x9ctriggerxe2x80x9d is broadcast along with the television video. The trigger identifies the information resource and indicates how information from the information resource is to be displayed.
Receiver unit 102 is a personal computer that has a television tuner card. One example of such a receiver unit is the xe2x80x9cWindows(copyright) 98 Broadcast PCxe2x80x9d system which includes a personal computer with the Windows(copyright) 98 operating system and a television tuner card. Windows(copyright) 98 is developed by and available from Microsoft Corporation of Redmond, Wash. In accordance with this system, an information resource is encoded into vertical blanking interval (VBI) lines 10-20 of an NTSC (National Television Standards Committee) broadcast television signal so that the information resource is transmitted to the receiver unit 102 along with the television video 105. At an appropriate time in the television video 105 when the information resource is to be displayed to enhance the television viewing experience, a trigger is broadcast. The trigger identifies the information resource and also serves as a queue to receiver unit 102 to display the information resource along with the television video. Receiver unit 102 responds to the trigger and displays the indicated information resource provided that the information resource has been transmitted to the receiver unit 102.
Receiver unit 103 is another type of interactive television receiver unit. In contrast to receiver units 100-101, receiver unit 103 retrieves information resources from the Internet that are identified by triggers. An example of such a receiver unit is a WebTV(copyright) set-top box Internet terminal. Television video 105 is broadcast from broadcast antenna 106 and is received on an antenna 115 of receiver unit 103. Consider the situation in which the broadcaster transmits a trigger that offers a viewer an option to buy an item by filling out an order form. At an appropriate time in television video 105, the broadcaster broadcasts a trigger 116 along with the television video. This trigger 116 causes receiver unit 103 to display an icon that offers the viewer the option of buying the item. If the viewer selects the icon using a handheld remote control unit 117, then receiver unit 103 retrieves from the Internet 113 via an Internet connection 118 an order form web page 119 identified by the trigger. Once the order form web page 119 has been retrieved from the Internet and displayed, the viewer can interact with the order form, enter user-specific information, and submit the user-specific information back to a merchant""s server on the Internet. It is therefore seen that receiver unit 103 enhances the television viewing experience by retrieving the information resource 119 identified by the trigger 116 and then displaying that information resource.
Receiver unit 104 is another example of another WebTV(copyright) interactive television receiver unit. This receiver unit 104, unlike receiver unit 103, is not able to retrieve an identified information resource from Internet 113. It is, however, nevertheless able to provide an interactive television experience. Consider the situation in which a series of information resources are already present on receiver unit 104 (for example, they may have been received in advance via VBI line 10-20 transport or they may be already be present on receiver unit 104 in the form of a compact disk of other storage medium). At various points in the broadcast television video 105, the broadcaster may transmit triggers identifying the information resources resident on receiver unit 104. These triggers may then cause the display of these information resources thereby enhancing the television viewing experience, provided that receiver unit 104 does not have to access the Internet to get information resources.
It is desired to be able to transmit triggers that utilize the full capabilities of both WebTV(copyright) receiver units 103 and 104, but a problem arises. If trigger 116 for the order form were transmitted to receiver unit 103, then that trigger 116 would also be received by receiver unit 104. This trigger 116 may cause the viewer at receiver unit 104 to be presented with an icon offering the viewer the option of ordering an item, wherein if the viewer selects the icon the item could not be ordered because the order form 119 could not be accessed. A solution is desired whereby the full capabilities of a receiver unit like receiver unit 103 and a receiver unit like receiver unit 104 can both be utilized in the same system.
In one embodiment, interactive television content is classified as either xe2x80x9cdisconnected contentxe2x80x9d or as xe2x80x9cconnected contentxe2x80x9d. In accordance with one such classification, disconnected interactive television content is content that, once present on the receiver unit, likely involves no further connection to the Internet. Connected content, on the other hand, is interactive television content that likely does involve an Internet connection.
An interactive television system in accordance with this embodiment involves some receivers that cannot establish connections to the Internet and therefore cannot properly process triggers to connected content. The system also involves other receiver units that can establish connections to the Internet and can process triggers to connected content. A trigger in accordance with this embodiment involves a connected content/disconnected content attribute that identifies the trigger as being either a trigger to disconnected content or a trigger to connected content. Receiver units that cannot process triggers to connected content can therefore use the attribute to identify triggers to such connected content and to ignore such triggers. Receiver unit failures and/or the display of options that are inoperative due to an inability to connect to the Internet are thereby prevented. Receiver units in the system that can establish connections to the Internet, on the other hand, can receive and execute both triggers to connected content and triggers to disconnected content. A functioning system having both types of receiver units is therefore possible.
In another embodiment, a relay station relays broadcast television video to receiver units that cannot establish connections to the Internet. This relay station uses the connected content/disconnected content attributes to identify disconnected content triggers, to retrieve the identified disconnected content from the Internet, and to relay that disconnected content to the receiver units. The relay station may, for example, encode such disconnected content into vertical blanking interval (VBI) lines 10-20 of an NTSC broadcast television video signal being relayed. The relay station also relays the triggers to the disconnected content. Because the receiver units receive both the disconnected content as well as the associated triggers from the relay stations, the receiver units can provide an interactive television experience using the disconnected content despite their inability to establish connections to the Internet.
In another embodiment, two triggers are broadcast for an enhancement. The first trigger alerts the relay station that disconnected content is to be prefetched from the Internet. The relay station prefetches the disconnected content identified by the first trigger from the Internet and relays it to the receiver units (for example, via VBI lines 10-20 of an NTSC broadcast television video signal) before the second trigger that actually triggers the enhancement on the receiver unit is received. In this way, the disconnected content is already present on the receiver unit when the second trigger arrives at the receiver unit. Accordingly, latency associated with having to retrieve and relay disconnected content identified by triggers is reduced.
Other aspects of the invention and other embodiments are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.